Bootstrapping a database for a test session

[brendonparker]

Hopefully this hasn't been asked before. Tried to search, but may not be articulating it in the same terms...

Problem Statement

I need to implement database-dependent tests with the following requirements:

1. One-time Database Setup

• Need to bootstrap a database (drop, run migrations) before tests
• Setup should run only ONCE per test session
• Setup should be shared across multiple test classes

2. Conditional Execution

• Bootstrap process should ONLY run if database-dependent tests are being executed
• If running tests that don't require the database, skip the bootstrap process entirely

Current Challenge

The main challenge is implementing this in a way that:

• Avoids redundant database setup for each test class
• Intelligently determines when database setup is needed
• Optimizes test execution time by skipping setup when unnecessary

Questions

What's the recommended approach to implement session-wide setup that only executes conditionally?
Is there a built-in mechanism in TUnit to detect which tests will be run in a session before execution begins?
Are there any existing patterns or utilities in TUnit for managing shared database resources across test classes?

Other Info

Its a multi-tenant database, so I can scope the test to a specific/random tenant, to keep tests from stomping on each other. Therefore I don't need a fresh db for every test, just one for the entire session.

What I've tried

1. Using a base class of DatabaseTest and adding an attribute [Before(Class)]. This worked great until there were multiple test classes. Apparently that applies to the derived classes and not just the base class.

2. Using the attribute [BeforeEvery(TestSession)]. This works for now, but still runs the method when any tests are run, not just tests that derive from DatabaseTest.

Thanks so much!

[brendonparker]

Here is my third attempt, which I think works well enough and may be enough of a solution, if no one has a better approach...

What I've tried (Part 3)

3. Use [Before(Class)] but detect if it has already ran...

[NotInParallel]
internal abstract class DatabaseTest
{
    private static int _invocationCount = 0;
    [Before(Class)]
    public static async Task Setup()
    {
        if (Interlocked.Increment(ref _invocationCount) > 1) return;

        await DropCreate();

        DatabaseMigrationRunnner.RunMigrations();
    }
}

[viceroypenguin]

Use a [ClassDataSource<>(Shared = PerAssembly)] and inject a fixture that sets up the db. The fixture should also implement IAsyncInitializer and IAsyncDisposable. You can see an example here:

• Fixture: https://github.com/viceroypenguin/VsaTemplate/blob/master/Web.Tests/Fixtures/ApplicationFactoryFixture.cs (more fancy than you need, but you can see the container construction in the InitializeAsync(); you can sed data in this method as well)
• Usage: https://github.com/viceroypenguin/VsaTemplate/blob/master/Web.Tests/TodosTests.cs See that it receives the fixture, and can use the fixture to get access to services and/or database context.

Alternative: Implement an IClassConstructor, store a reference to shared needs in a static field, and apply [ClassConstructor<>] to the test classes. The static field will implicitly be constructed by the runtime exactly once per test-run, etc. Docs here: https://thomhurst.github.io/TUnit/docs/tutorial-extras/class-constructors

Both of these solutions should, in theory, only run if you are running tests inside of classes that have one these attributes. Though they are assembly-wide, they are not constructed unless used.